When the banking blog asks insiders who they blame for the financial crisis, most say: the rating agencies. It was the rating agencies that assigned super safe ("triple A") ratings to complex financial instruments. When these blew up, the agencies accepted no responsibility, claiming they had merely been expressing "opinions".

William J Harrington was a senior analyst at rating agency Moody's between 1999 and 2010 in New York. Since then he has been campaigning for reform and drawing attention to ongoing problems with ratings. Bill is coming into the comment threads below to answer your questions and discuss his views.

Some of Bill's quotes hint in one sentence at a whole universe of dysfunction: "In my days it was individual managers [at Moody's] who set the rules on how to interact with the bankers: for instance whether we could scream back at them (we could not)." And: "I knew rating agencies were seen in the industry as losers and 'also-rans'. I didn't care. I didn't go to conferences, to industry parties… The reality is rating agencies attract rather different kinds of people."

The most shocking thing, at least for me, was this:

"The CEO of Moody's in the runup to the fiasco in 2008 is now… still the CEO of Moody's. Last year his compensation was $6m, in line with his five-year average. Moody's has never had a losing quarter. This is why analysts who follow Moody's for investors really like Moody's. Moody's always makes a profit."

Bill says he has asked people at Moody's why those responsible weren't fired. "That would be an admission of liability, I was told. Worse, precisely the managers responsible for the instruments that blew up have been rewarded and promoted. I don't believe in conspiracies but here you really have a small cabal of people doing this."

Free market theory predicts that when market players perform as badly as the rating agencies have, new companies will see an opportunity. This has hardly happened with the market for rating agencies. Bill: "Rating agencies form an oligopoly, with Moody's, Fitch and S&P controlling 97% of the market between them. If there were many significant rating agencies of varying sizes and ownership structures rather than three indistinguishable large ones, then if a few changed their approach it would be hard for the rest to simply continue to go along for the ride. Currently, this is not a self-correcting system."

But why don't other players in finance demand better rating agencies? After two decades at the top of his profession, Bill offers this bleak assessment:

"The rating agencies are such small entities in such a huge industry. They are like the Panama canal. Crucial but very small. Worldwide, the nine big registered rating agencies have less than 4,000 junior and senior analysts working for them, combined across all activities. JP Morgan alone employs a quarter of a million people. This state of affairs seems to suit the big players well. The rating agencies are one moving piece in the machine that they can push around.

"The rating agencies have been the all-purpose bogeymen for the crisis. They bear a heavy responsibility, absolutely, but this exclusive focus obscures how the problems are embedded in the whole system: the big banks, accountancy firms, financial law firms, investment firms, regulators, the financial press… The rating agencies have done us a disservice by allowing so much of the blame to rest on them. They are effectively protecting these other players – who seem quite happy with this arrangement. Meanwhile people at rating agencies go: "just blame us, we're used to it."

It's very rare for a former rating agency employee to speak out like Bill does: "I didn't take 'a package'. If I had I might have gotten a year's salary – but I'd have to sign a 'non-disparagement' clause which meant that I'd remain silent about what I saw."

There is much more good stuff in the full interview, about how the rating process actually works, how rating agencies reward their employees in a fundamentally different way from other areas in finance, and what it's been like for Bill to be gay in finance.

Especially if you're considering leaving a comment below, please read the full text first. As for those comments, it would be really great if other (former) rating agency employees would come forward. Equally interesting would be to hear from insiders across the financial industry about their experiences with the rating agencies. At the end of the full text Bill makes two alarming points about ongoing problems with ABSs. What do other insiders think?

As for financial outsiders: this is your chance. Bill had a ring seat during the buildup, climax and aftermath of the 2008 financial crisis. A firm believer in disseminating information and insight about finance to as large an audience as possible, he is eager to take your questions, also those about finance generally.

• This banking blog features interviews with insiders across the industry. Here is a guide to help you find your way.

One other rating agency employee has spoken to the blog: "Every time I read about a new financial product, I think: 'Uh-oh'."

Another voice in finance who is gay: "When I came out, my boss was really supportive and so were my colleagues. There has been only one idiot so far."